Field
The present disclosure relates generally to clamping devices. In particular, the present disclosure relates to clamping devices for electrochemical cell stacks.
Description of the Related Art
A lithium ion battery typically includes a separator and/or electrolyte between an anode and a cathode. In some of batteries, the separator, cathode and anode materials are individually formed into sheets or films. Sheets of the cathode, separator and anode are subsequently stacked or rolled with the separator separating the cathode and anode (e.g., electrodes) to form the battery. For the cathode, separator and anode to be rolled, each sheet must be sufficiently deformable or flexible to be rolled without failures, such as cracks, brakes, mechanical failures, etc. Typical electrodes include electrochemically active material layers on electrically conductive metals (e.g., aluminum and copper). For example, carbon can be deposited onto a current collector (e.g., a copper sheet) along with an inactive binder material. Carbon is often used because it has excellent electrochemical properties and is also electrically conductive. Electrodes can be rolled or cut into pieces which are then layered into stacks. The stacks are of alternating electrochemically active materials with the separator between them.
In order to increase the volumetric and gravimetric energy densities of lithium-ion batteries, silicon has been proposed as the active material for the negative electrode. However, during cycling, silicon particles in the anode active material expand upon charging. This expansion can deform the metal foil used as current collectors. Since the layers of the cell stack are confined in a tight region, the expansion can result in warping or deformation of the metal foil, thus reducing the contact area between layers in the battery stack. As a result, the ability of a battery to accept and release electrical charge may be severely affected. Thus, preventing the electrode from deformation could serve to reduce the irreversible capacity and improve cycle life.